The C IV forest as a probe of baryon acoustic oscillations

Abstract

In light of recent successes in measuring baryon acoustic oscillations in quasar absorption using the Lyman $\alpha$ (Ly$\alpha$) transition, I explore the possibility of using the 1548Å transition of triply ionized carbon (C IV) as a tracer. While the Ly-alpha forest is a more sensitive tracer of intergalactic gas, it is limited by the fact that it can only be measured in the optical window at redshifts $z>2$. Quasars are challenging to identify and observe at these high-redshifts, but the C IV forest can be probed down to redshifts $z\approx 1.3$, taking full advantage of the peak in the redshift distribution of quasars that can be targeted with high efficiency. I explore the strength of the C IV absorption signal and show that the absorbing population on the red side of the Ly-alpha emission line is dominated by C IV (and so will dominate over the potential BAO signal of other metals). As a consequence, I argue that forthcoming surveys may have a sufficient increase in quasar number density to offset the lower sensitivity of the C IV forest and provide competitive precision using both the C IV autocorrelation and the C IV-quasar cross-correlation at $<z>\approx 1.6$.

6 pages, 3 figures. Final version published in MNRAS Letters

References in corpus (4)

• Baryon Acoustic Oscillations in the Lyα forest of BOSS DR11 quasars
• Baryon Acoustic Oscillations in the Ly-α forest of BOSS quasars
• Metal-line absorption around $z\approx$2.4 star-forming galaxies in the Keck Baryonic Structure Survey
• Dark energy and curvature from a future baryonic acoustic oscillation survey using the Lyman-alpha forest

Cited by in corpus (4)

• The extended Baryon Oscillation Spectroscopic Survey: measuring the cross-correlation between the MgII flux transmission field and quasars and galaxies at $z=0.59$
• The cross-correlation of galaxies in absorption with the Lyman $\alpha$ forest
• Constraining IGM enrichment and metallicity with the C IV forest correlation function
• The Cosmic Evolution of CIV Absorbers at $1.4<z<4.5$: Insights from $100,000$ Systems in DESI Quasars